Optical detection in microfluidic systems

Abstract

Optical detection schemes continue to be favoured for measurements in microfluidic systems. A selection of the latest progress mainly within the last two years is critically reviewed. Emphasis is on integrated solutions, such as planar waveguides, coupling schemes to the outside world, evanescent-wave based detectors and the field of optofluidics. The perspectives and limitations of the different solutions are discussed in terms of analytical performance and fabrication costs. There has been an increased focus on cheap solutions in polymer materials that are amenable for mass production in order to ease commercialisation of the devices. This work will hopefully result in more commercial products that benefit from integrated optics, because the impact on commercial devices so far has been modest.

Femtosecond laser microstructuring: an enabling tool for optofluidic lab‐on‐chips

“…Several efforts have been performed in order to fabricate on-chip micro-optical components to perform optical detection [14][15][16]. The most widely used components are optical waveguides, which allow to confine and transport light in the chip directing it to a small volume of the microfluidic channel and collecting the transmitted/emitted light.…”

“…Depending on the substrate of choice, different methods can be used. Approaches reported in the literature include waveguide fabrication by silica on silicon [14][15][16][17], ion exchange in soda-lime glasses [18,19], photolithography in polymers [20,21] and liquid-core waveguides [22][23][24][25]. All these methods suffer, when applied to LOCs, from several limitations: (i) they are inherently planar techniques, i. e. they are able to define optical guiding structures only in two dimensions, close to the sample surface; (ii) they are multistep methods, involving multiple masking with critical alignments; (iii) they require cleanroom environment, and (iv) they typically create uneven surfaces which make sealing of the microfluidic channels problematic.…”

Microfluidic Bioreactors for Cell Culturing: A Review

“…Despite these draw backs optical sensing elements still dominate over other detection systems such as electrochemical methods. These optical detection methods have been discussed in a number of reviews [146][147][148]. For future, we are likely to see increasing integration of optical elements, e.g.…”

A microfluidic erythrocyte sedimentation rate analyzer using rouleaux formation kinetics

“…For devices, which utilize optical measurement/detection mechanism, vibrations can interfere with the measurement results by increasing the baseline noise level (Mogensen and Kutter 2009;Myers and Lee 2008). Therefore, we also investigated the measurement performance of the system when the device is mechanically disturbed.…”